High-density, small form-factor battery cells have recently been proposed for use in high cell-count automotive and industrial battery packs. The small form-factor cells have a larger surface-area-to-volume ratio than larger cells, and thus provide the potential for better cooling efficiency. Also, because each small form-factor cell constitutes a smaller portion of the overall energy capacity of the pack, single cell failure is more tolerable than in the case of large-cell battery packs.
Like most battery cells, small form-factor battery cells tend to degrade when subject to elevated temperatures. For example, lithium-ion batteries lose 20% of their usable charge within three months when subjected to 60° C. temperature. In contrast, they will lose the same percentage of charge in three years when the temperature is held at 25° C. Therefore, it is important to keep the battery cells cool and maintain a constant temperature across the cells, a substantial challenge in a high cell-count battery pack which can generate tremendous amounts of heat under load. As an example, conventional circulating-liquid manifolds typically have many inlet and outlet connections and thus are susceptible to liquid leakage which may short electrical connections and/or damage system components.